• Apr 23rd 2009 at 11:58AM
  • 32
Can you run a car on compressed natural gas? Yes, you can. Wow, that was easy. I guess we can wrap up this week's Greenlings post quickly. Not so fast. Like just about everything else in this world, the full answer is much more complicated than the simple yes. Here in the United States, there are but a handful of vehicles available that are equipped from the factory to run on CNG, and there are even fewer places to get those vehicle's gas tanks topped off with the stuff. Have a car that you want to convert? That's great, but a number of major modifications are required to run a vehicle on natural gas if it was originally intended to burn gasoline.

For these reasons and a few more, just one tenth of one percent of all natural gas consumed in the United States is currently used for transportation. Most of it is used to generate electricity and to heat people's homes and food. That's a shame, as liquefied and compressed natural gas hold significant promise as a viable alternative to other fossil fuels in the transportation sector. How so? Click past the break to keep reading this week's Greenlings.

Why use compressed natural gas in the first place, and why use it for cars?

For one, CNG is cheaper than gasoline or diesel. Lots cheaper, in fact – in some cases about a third of the price of an equivalent amount of gasoline. In addition, natural gas burns significantly cleaner than other fossil fuels.

The United States EPA lists the following statistics about vehicles running on natural gas:
  • Reduce carbon monoxide emissions 90%-97%
  • Reduce carbon dioxide emissions 25%
  • Reduce nitrogen oxide emissions 35%-60%
  • Potentially reduce non-methane hydrocarbon emissions 50%-75%
  • Emit fewer toxic and carcinogenic pollutants
  • Emit little or no particulate matter
  • Eliminate evaporative emissions
Those are all great reasons to want a car that runs on natural gas, but there are others that are equally as important. For instance, when CNG is released into the atmosphere, it disperses quickly since it's lighter than air, so it's not harmful to someone standing next to the car. Lastly, the majority (about 87 percent) of natural gas here in the United States is sourced locally, not from other countries.

What vehicles are currently available that use natural gas?

Here in the U.S., the list is tiny. There's the Honda Civic GX and the... um, well that's it from the major manufacturers, at least on the consumer level, and the GX is only available in California and New York. At least it's a solid choice. The United States EPA rates the Civic GX as the cleanest car available in America.

Further, the automotive CNG industry was dealt a serious blow earlier this month when Fuelmaker, a producer of natural gas refueling systems, was forced into involuntary bankruptcy by parent company Honda.

Many automakers currently produce vehicles equipped to run on CNG for fleet or government use. All told, there are currently 120,000 natural gas vehicles on the road in America, which is a tiny number in comparison to the millions of gas and diesel vehicles. According to Wikipedia, there were over 7 million natural gas vehicles on the roads worldwide in 2008, mostly in Europe, Asia and South America.

Are there any drawbacks to using natural gas in a vehicle?

Of course there are. Besides the fact that there's only one actual production CNG vehicle in America, there are other reasons why consumers don't often consider CNG a viable option. One big drawback is that it's more difficult to refill the fuel tank of a car that runs on natural gas. Another problem is that the storage tanks required for natural gas are big and bulky, so there's a give-and-take relationship between how much fuel is carried and how far you can travel.

Finally, there aren't all that many places to refuel a natural gas vehicle. The U.S. Department of Energy operates a website with natural gas filling stations that you can find here. Check the box for compressed natural gas, enter your zip code and have at it.

What does the future hold for natural gas vehicles?

One of the most well-known proponents of natural gas for transportation is T. Boone Pickens, a man who made most of his fortune on oil. Now, Pickens is pushing forward with a plan to divert the natural gas that's currently used to generate electricity to our transportation sector. Of course, that would offer little help without a corresponding increase in the number of vehicles that run on natural gas. There have been concept CNG vehicles like the CNG Camry Hybrid and Mercedes-Benz B-Class, but so far no more automakers have announced plans to offer natural gas vehicles in the U.S.

If you don't want to wait for more major manufacturers to begin producing natural gas vehicles, there are a number of companies out there that will convert your car to run on natural gas. The U.S. Department of Energy keeps a list of companies that offer conversions, click here to check it out.

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    • 1 Second Ago
      • 6 Years Ago
      I think most people get it wrong when they look at replacements for unleaded gasoline. It is not a zero sum game, I don't have to drive a dedicated single fuel vehicle. My Nissan X Terra can hold 20+ gallons of unleaded, however the I only have to give 50% of cargo area to put the 10 GGE CNG tank in (assuming 3200 psi fill).

      I can drive everywhere in the US and still get gas. The car is a dual fuel. The real clincher is that I can drive locally on entirely CNG. When you consider that over 90% of my driving is local that really begins to add up. I also travel a fair amount for work and have had no problem finding relatively convenient CNG filling stations in most of the western states (except for Idaho).

      At the end of the day I think that creating cars that can run on multiple fuel sources is the real answer:
      Methane + Diesel
      Diesel + CNG
      Unleaded + Electricity + CNG
      CNG + Unleaded


      *you cna buy a new CNG GX in almost every state, not just CA and NY
      **there a lot more in home fueling solutions just FuelMaker, it concerns me that the Fuelmaker bankruptcy is getting so much press as a death-nail to CNG. A simple google search will turn up others.
        • 6 Years Ago
        What about the points I made above?

        Alcohol makes more sense as an alternative fuel.

        No need for bulky heavy high-pressure gas canisters that eat up passenger or cargo space.

        Instead, you'd have ONE large fuel tank that can be any irregular shape, filled with gasoline, methanol, ethanol, or any other alcohol, in any mix or none at all. No settings to set, no switches to throw, all seamless and automatic and user-free.

        And you can make methanol from natural gas cheaply, so NG plays a role, but merely as a feedstock for a much more convenient and practical alternative fuel.
        • 6 Years Ago
        You and I are singing the same song on creating substitutes. The array needs to be broad and deep. If the community gets to dependent on one or another fuel source (be it methanol or CNG or Electricity) then we step into the same problem that we are in right now.

        When I lived in Brazil cane based ethanol made sense, it was temperate all year round. Furthermore cane grew like a weed. I think it would be much harder to implement an electric grid system in all but the major cities in Brazil - the infrastructure could not support it. However, in UT Ethanol or Methanol would only work for 8 months out of the year as it is too cold the rest of the year the fuel begins to gel and loses functionality (I don't know enough about the energy cost process to convert Methane to Methanol to talk to that point intelligently) but, Utah could support an electric grid...

        The solution is varied and wide, the more people evangelize any one solution as THE SOLUTION, we will continue to run into problems. From where I sit groups like the EPA and certain Gov. entities that restrict laws around innovation and exploration of viable substitutes are the real problem. How is any alternative fuel source going to gain traction if every innovation is deemed illegal and not road worthy.

        One of the first innovations needs to be in creating a certification process for a wide array of small and local groups to begin making street-legal conversions of many different types of fuels. Then incentivizing the early adopters (read: early consumers) of these conversions so that the capitalistic process of innovation, competition, and adoption can begin to take place.

        • 6 Years Ago
        Chad, I actually disagree with you.

        I think our unfocused approach and lack of a sound and coherent strategy has crippled all efforts to move beyond oil.

        It's true that alcohol isn't perfect in part because of the need for 15% gasoline in non-tropical climates, but that is such a huge improvement as to be worth it (unlike hybrids). Also, much of that 15% gasoline can be replaced down the road with butanol.
      • 6 Years Ago
      Civic GX only available in CA and NY? My local Honda dealer had one in stock a few months ago when I was checking out the Fit, and I was parked next to a different one at Target last month. I am in neither NY nor CA, but North Carolina.
      • 6 Years Ago
      How does CNG compare to LP in terms of energy density and engine conversion? Can a car converted to LP run on CNG? Could LP pumps handle CNG?
        • 6 Years Ago
        Propane and Butane, the two main components of LPG, will liquefy under pressure at room temperature. Methane and Ethane, the two main components of natural gas, will not liquefy at room temperature regardless of pressure. That allows a typical LPG tank to store more fuel than a CNG tank. Fuel metering, orifice size, and pressure regulation is different, too.

        Sorry, but it isn't a good idea to try and combine CNG and LPG in one tank. Choose CNG for lower price but less range, LPG for longer range per tank, but slightly higher price.
      • 6 Years Ago
      87% maybe produced locally, but the other 12-13% is produced in mexico and canada and piped in just over the border.... Very little is actually put on vessels and shipped in, although we may be getting a small amount from offshore.

      CNG is great, the tanks are safe if built well, even if they aren't, and they explode, things disperse very quickly. They're actually safer than gas tanks. I've seen movies of a full tank of CNG sitting on a pile of burning pallets and it did nothing. One was fixexd to the front of a car and dropped .... nothing.

      The biggest PROBLEM in the US is that the EPA is regulating conversions. In order to certify it, the emissions of the conversion must be guaranteed. Right now, mostly ford and chevy trucks are certified, as well as the Honda GX and a couple other small cars. There are kits available, but they have not been tested to comply with emissions. Their big concern is NOx emissions. If we can get more kits certified on some of the most popular cars here in the US, we could move forward. The conversion kits and tank aren't outrageous.... but finding a way to fill your tank might prove problematic.... since fuelmaker just bit it.

      Just think, CNG and electric hybrid... locally produced fuels. It may not be the cleanest solution, but its a step in the right direction and will help the US with dependance on foreign oil.
      • 6 Years Ago
      America's almost complete disregard of the use of propane in anything but dragsters is one of the greatest mysteries in the alternative fuel world, just behind the late adoption of diesel.

      Anywhere you are, Liquified Petroleum Gas costs less than gasoline, partially because it's only a derivative... propane is also a by-product of some of the processes used to create other biofuels.

      Tooling up for dispensing propane is so ridiculously inexpensive that when oil shot to over $100 a barrel, propane stations cropped up in our tiny third world country literally overnight. I was looking at one of those pumps and wondering if I ought to equip one in my garage.

      The most any car will need to convert to propane is an extra set of injectors (new propane injectors have duty-cycles that are very similar to gasoline injectors), a fuel tank, an evaporator (to convert liquid to gas) and a computer that translates your gasoline fuel map into a propane fuel map. A total outlay of about $1000-$2000. Equip the car from the factory with an ECU that can handle dual fuel mapping, and $500 can be knocked from that cost.
      • 4 Years Ago
      Are you quoting the Heartland Institute with a straight face?
      • 6 Years Ago
      To answer the question regarding NG's supply and source, as someone above pointed out, yes, the US currently imports approximately 20% of its NG. But most if not all of that comes from those crazy terorists up north, the Canadians, (okay, they're not crazy or terrorists, eh?).

      Modifying that in the future will be the Alaskan NG Pipeline, ( http://www.gov.state.ak.us/agia/ ). It is estimated that the reserves there are over 16 trillion cubic feet. That's enough to run every transportation vehicle in the US for over 30 years.

      As far as the Fuelmaker patents for the Phill, they now belong to California-based Fuel Systems (FSYS), the builder of the IMPCO(?) line of aftermarket CNG adapter kits.

      Currently we send over $40bn USD MONTHLY overseas for petroleum, most of which goes into our transportation conveyances. Being able to internalize these monies back into our economy would create jobs, strengthen our currency and de-fund nations that are behind terrorists around the world.

      What needs to be done? Congress and the President have to make it clear in no uncertain terms that this is the direction this country is going to go via legislation that encourages not only the use of NG but the education process to train people to build Home-Fueling-Appliances, (HFAs), people to install and service them, constructing the infrastructure to replace gasoline/diesel fueling stations to CNG cascade stations, CNG tank construction plants and finally but not the least, revitalize the American steel processors who will make the steel we need to do all this. Add to that the streamlining of the approval process so more vehicles qualify for retrofits in states that restrict which types of vehicles can be retrofitted, such as California.

      What can you do? Americans can call, write or email their congress-person, senator and President and make your wishes known. This can all be achieved, but it's going to take an effort that is very much like a war-footing, where the attention and resources of the nation are focused to bring this about. If all this sounds a little pie-in-the-sky, ask yourself this. Why ISN'T it unpatriotic to support the use of gasoline and diesel? Shouldn't it be? Change will come about when the general opinion in society is that the use of those products are either arcane or antisocial.

      • 6 Years Ago
      my question is about volume. In a car converted to run on CNG how much of a loss of range do I get with the same size tank? I drive 100 miles per day and if I can't have a least a 400mi range I wouldn't even consider it.
        • 6 Years Ago
        The short answer is that an equivalent number of gallons (GGEs) of CNG required 4.7 times the space. You can either give up range and sacrifice some trunk space etc. for additional fuel storage.
        • 6 Years Ago
        I don't know. But why would you want to make diesel out of NG?

        Diesel is also incompatible with gasoline, ruling out long or spontaneous trips.

        But methanol, which CAN be made from NG, IS compatible with gasoline in a fully flex-fueled vehicle.

        And alcohol fuels burn much more cleanly than NG, gasoline, and certainly diesel.
        • 6 Years Ago
        It's a bit hard to compare.

        You'll see that CNG is sold in GGE's to help that comparison. Since it's a gas not only volume but PSI counts.

        See this page:


        "One GGE of natural gas is 126.67 cubic feet. This volume of natural gas has the same energy content as one US gallon of gasoline (based on lower heating values: 900 BTU/CF of natural gas and 115,000 BTU/gallon of gasoline).[11]

        One GGE of CNG pressurized at 2,400 psi is 0.77 cubic feet. This volume of CNG at 2,400 psi has the same energy content as one US gallon of gasoline (based on lower heating values: 148,144 BTU/CF of CNG and 115,000 BTU/gallon of gasoline.[11] Using Boyle's Law, the equivalent GGE at 3,600 psi is 0.51 cubic feet which corresponds to 14.5 liters or 3.82 actual US gallons.

        The National Conference of Weights & Measurements (NCWM) has developed a standard unit of measurement for compressed natural gas, defined in the NIST Handbook 44 Appendix D as follows: "1 Gasoline [US] gallon equivalent (GGE) means 2.567 kg (5.660 lb) of natural gas."[12]

        When consumers refuel their CNG vehicles in the USA, the CNG is usually measured and sold in GGE units. This is fairly helpful as a comparison to gallons of gasoline."
        • 6 Years Ago
        So in other words with a 3600psi tank that is physically the size of my 15 gallon gas tank I only get 3.93 GGE of CNG dropping my 400 mile range down to 105 miles? Doesn't sound very ideal to me. Plus a 3600psi tank would likely have to be cylindrical which really limits the ability of designers to efficiently use space.

        Is there any way to make diesel out of NG? I personally would rather get a 700mile range from my 15gal tank than 105miles.
        • 6 Years Ago
        I don't know. I doubt it is worthwhile. See my post above. NG can be made into methanol, a far cleaner liquid fuel than diesel, and one which is gasoline compatible in flex-fuel vehicles.
      • 6 Years Ago
      One thing that is not mentioned is that methane is an incredibly effective greenhouse gas. The cross section for IR absorption of a methane molecule is about 40X that of a CO2 molecule. So if you're doing this for global warming reasons, you better make sure you aren't leaking ANY methane into the air. Even a trace amount will become a significant source of heat trapping.
      • 6 Years Ago
      CNG or LNG are viable solutions because we have the reserves and the technology, it is cleaner and cheaper, but apparently our lobbyists don't have the will.
      • 6 Years Ago
      The Civic GX never sold well because it cost more than even the Civic Hybrid and offered relatively poor mileage (24 mpg-equivalent city, IIRC)

      LPG/gasoline "dual-fuel" vehicles are popular in developing countries, where locally-produced LPG is significantly cheaper than imported gasoline.
      • 6 Years Ago
      Honda's CNG Civic has been available to California residents for quite some time, but it never really caught on. I think CNG just doesn't carry the psychological impact that electricity or hydrogen does.
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